Electrolytes and muscle cramps: what to know

Sodium, potassium, calcium and magnesium help control fluid movement, nerve signals and muscle contraction. Sweating, vomiting or diarrhoea can alter this balance. A cramp is a sudden, involuntary tightening, often in the calf, foot or thigh. A muscle strain can cause local pain, while circulation problems may cause leg discomfort with walking. Repeated cramps can also occur with thyroid, kidney, vitamin D or muscle-mass conditions; the symptom alone does not identify the cause.

Stop the activity and gently stretch the affected muscle; light massage and warmth may help it release. Replace fluids after heavy sweating, and eat regular meals with varied foods rather than taking concentrated electrolyte products without advice. Keep a note of triggers, timing, body area, medicines and associated weakness. A clinician can review these details and decide whether an examination or blood tests are appropriate. See information on [Dehydration](/conditions/dehydration/) and [Muscle Cramps](/symptoms/muscle-cramps/).

Arrange medical advice if cramps are frequent, severe, worsening, disturb sleep, or begin after a medicine change. Seek urgent help for a cramp with marked weakness, confusion, fainting, chest symptoms, breathing difficulty, a swollen painful leg, or inability to use the limb. Prompt assessment is also sensible when cramps follow persistent vomiting or diarrhoea, or occur in someone with kidney disease.

Could my medicines, fluid intake, exercise pattern or diet be contributing? Do I need electrolyte or kidney-function tests? What stretching and fluid plan suits my health conditions?